The answer is yes. Not all yeast producers, including the one sourcing the Shaw's yeast product, use the identical strain of yeast. However, ideally, one would hope that the variations from one brand of a particular form of yeast to another, even house brands, will be small so that recipes can be practiced to produce fairly consistent results. Your question is timely inasmuch as I discussed this topic in some detail yesterday in response to questions raised by Norma, at Reply 1938 at http://www.pizzamaking.com/forum/index.php/topic,21559.msg256232.html#msg256232.

Thanks Peter. I was waiting for your reply. So from what you said to Norma on a commercial level; yeast can vary even slightly from what they sell at retail. Is this because yeast will sit longer on shelves at a retail store compared to a supply store? IIRC I was using the SAF IDY, which looked like ball bearings, the yeast in the jar has a more tube like look. Do you think when I switch over to a commercial IDY there will be a big difference? I'm using very small yeast amounts btw, measuring in the thousandths of a gram for accuracy and consistency.

http://www.breadworld.com/products.aspx the Fleischmann's web page clearly states that their "bread machine", "rapid rise", and instant yeast are all the same. Other companies may vary, but it is highly unlikely.

Thanks Peter. I was waiting for your reply. So from what you said to Norma on a commercial level; yeast can vary even slightly from what they sell at retail. Is this because yeast will sit longer on shelves at a retail store compared to a supply store? IIRC I was using the SAF IDY, which looked like ball bearings, the yeast in the jar has a more tube like look. Do you think when I switch over to a commercial IDY there will be a big difference? I'm using very small yeast amounts btw, measuring in the thousandths of a gram for accuracy and consistency.

David,

Yeast products are highly proprietary products so you are unlikely to get much help from the producers of those products, if you can even find persons at the companies who know enough to be able to answer technical questions. It took me quite a while to get one of the major yeast producers to tell me that there were differences between their retail and professional brands. I also recall that they wouldn't compare their brands of yeast products with their competitors' products. My own thinking is that there may be differences between retail brands and professional brands but they are likely to be minor. I sometimes wondered whether there were no differences but that they did not want to tell consumers that. It is in their best interests to have consumers continue to buy the retail brands in packets where the profits are enormous compared with the professional products sold in bulk.

I think it is also important to keep in mind that the leavening power of yeast products declines with age, especially after the package is opened, and also with varying storage conditions. So, even if yeast is weighed, there is no assurance that the measured yeast will be the precise amount you want to use. I don't know if the frequency or rate at which yeasts products are used is reflected in the retail and professional yeast products. If I had thought of that possibility, I would have asked about it.

http://www.breadworld.com/products.aspx the Fleischmann's web page clearly states that their "bread machine", "rapid rise", and instant yeast are all the same. Other companies may vary, but it is highly unlikely.

I read that myself a few years ago and, as a result, I approached Red Star on this matter. You can read the exchange at Reply 13 at http://www.pizzamaking.com/forum/index.php/topic,10707.msg95811.html#msg95811. In retrospect, it occurs to me that Carol at Red Star may not have appreciated that our members know that there are quantitative differences (different baker's percents) between ADY and IDY. I have seen many recipes directed to home bakers that make no distinction between the two forms of yeast from a quantitative standpoint. In this respect, you will note that an envelope of ADY and an envelope of IDY both weigh 1/4-ounce, or 7 grams.

I should also point out that if you go to the recipes section of the Fleischmann's website, and look at the pizza related dough recipes, they invariably call for large amounts of yeast, as much as a full envelope or even two envelopes. So, their orientation is the home consumer market where convenience, speed and time are of the essence, not the professional market. I wrote on this latter subject years ago, including at Reply 13 at http://www.pizzamaking.com/forum/index.php/topic,407.msg4652/topicseen.html#msg4652. Since that time, the yeast producers have come up with new yeast products, such as the Fleischmann's Pizza Crust Yeast, but the recommended usage is still a full envelope. You will be hardpressed to find pizza dough recipes on the Fleischmann's website that call for ADY, even though ADY was specifically invented after World War II for the home consumer market. IDY came into being in the 1970s and has pretty much crowded out ADY for ordinary home bakers. Our members are more aligned with the professional side of pizza dough making.

I was also surprised at there recommended amounts, they said it takes a packet from the 3 strip standard to raise a recipe with 4 cups of flour! I routinely make my pizza dough recipe with 4 cups of flour and use a scant teaspoon of yeast.